1. Field of the Invention
The present invention relates generally to medical devices and methods, and in particular to a device and method for removing edema fluids from a body trunk and/or extremity such as an arm or a leg.
Breast cancer is a serious disease in women, and a variety of modalities are employed in its treatment. Many of these treatments result in damage to the lymphatic and/or venous system which, in turn, can cause a condition referred to as "lymphedema." Lymphedema is the accumulation of excessive lymph fluid and swelling of subcutaneous tissues due to the obstruction or destruction of lymph vessels. In breast cancer patients, lymphedema occurs in the arm and results in painful swelling. Excessive fluid accumulation, referred to as edema, can also arise in the arms, legs and, trunk from a variety of other causes, including infection, radiation therapy, and other conditions which result in damage to or destruction of portions of the lymphatic and/or venous system.
2. Description of the Background Art
A variety of devices and methods have been proposed for the treatment of lymphedema in the arms and elsewhere. Many such devices utilize a sequential pump which works like a multiplicity of blood pressure cuffs extending from the shoulder to the hand, which contract and expand individually. When pressure is exerted by any one chamber or cuff, it applies a `blanket pressure` (i.e. an annular pressure which completely circumscribes the limb or other body portion) to the skin directly underneath the area of that chamber. When the pressure upon that area is released, a similar blanket pressure is then applied to the portion of the arm covered by the next adjacent chamber, and so on up the arm. Such blanket pressures are applied sequentially from the distal to the proximal ends of the arm, with the intention of forcing the fluids up the arm and into the trunk of the body, where existing lymph nodes can process them.
Another prior mode of treatment has been a double walled sheath or stocking in which air pressure is introduced between the walls to squeeze the limb. It has been found that this and other similar systems, which rely on uniform blanket pressure application through the length of the afflicted limb or portions thereof, do not perform very well and in fact may interfere with the desired distal-to-proximal flow of lymphatic fluid.
We have found that when a uniform and/or excessive pressure is applied to an area for the purpose of moving fluid, the opposite effect may result. In particular, the application of pressure may: 1) compress the veins and lymph ducts, resulting in blockage; 2) augment capillary leak; and 3) prevent the lymphatic fluids from mobilizing.
Other approaches to treatment have included employment of a sheath that is separated into a number of longitudinally spaced inflatable air cells encircling the limb to be treated. These cells are successively inflated with uniform air pressure from the distal end to the proximal end of the sheath with the intent of promoting fluid flow in the desired direction. Such systems have been largely ineffectual, as they rely on air pressure being maintained at the same level or magnitude in any one of, or all, of the pressurized cells, producing a blanket effect. U.S. Pat. Nos. 2,533,504 and 2,781,041 disclose examples of such systems.
Prior U.S. Pat. No. 4,370,975 discloses an apparatus for treating lymphedema and similar fluid retention afflictions through the use of a multi-cell inflatable sheath which encompasses the swollen limb. Pressure is applied in the cells of the sheath in timed sequence from the distal cell to the proximal cell, the sequence of pressure applied also defining a decreasing gradient pressure from a maximum pressure applied in the distal cell to a minimum pressure applied in the proximal cell when all of the cells are pressurized. Generally, for each of the adjacent cells the more distal has applied a higher pressure than the more proximal. This application of gradient pressure from distal to proximal cells in time sequence comprises a cycle, and such cycle may be repeated indefinitely to promote the flow of lymphatic fluid from the afflicted limb in a proximal direction.
The problem with the above methods is that any form of blanket pressure such as that applied by pneumatic or hydraulic pressure to large afflicted areas will have at best a minimal result.
Carter, 5,063,910 shows an apparatus for treating vascular, metabolic and functional imbalance of a limb by variations in pressure of a high-density fluid, such as a mercury bath, around the limb.
The problem with this device is that the pressure applied by this means is, in fact, a blanket-pressure, which increases with the depth of the limb portion within the fluid bath, resulting in the disadvantages described above for al other pressure systems. Another disadvantage is that the patient must remain immobilized during treatment.
R. W. Lilligren et al, U.S. Pat. No. 3,454,010, shows a hollow tube-like bandage for wrapping in a spiral-like manner around the limb of a patient, into which is then applied a pneumatic pressure, which is intended to drive out excess fluids prior to surgery.
Once again the pressure applied is a uniform or blanket pressure to the skin, and so is relatively ineffective to reduce swelling.
Ewen, U.S. Pat. No. 5,257,956, shows a garment for use by post-mastectomy patients which alleviates post-operative pain and discomfort and facilitates normal activity during the recovery period. A padded vest-like garment is adapted for applying comforting pressure to the sites of removal of breast and other tissues and for holding pain relieving packages.
Again, the problem with this garment is that it applies a blanket pressure, resulting in little reduction in swelling.
Fregealle, U.S. Pat. No. 3,975,929, shows a stocking knit on a circular knitting machine which provides a gradually decreasing compressive force on the leg of the of the wearer from the ankle upwardly to the top of the stocking. Again, we believe that a uniform or blanket-pressure such as is applied by this device, is not the best method for forcing out excess lymphedema fluids.
In all of these pressure-applied methods, the patient is immobilized up to 4 hours per day, and sometimes several days in succession, suffering following treatment and soreness of the arm for many days afterwards.
It is a well established fact that special exercises following mastectomy help to mobilize lymphedema fluids; yet prior art devices contribute toward immobilizing the patient, making exercising difficult or impossible. Thus resulting in a counter-producing effect.
The cost of sequential pumps including necessary limb compression apparatus range from $500 to over $8,000. In addition, skilled technicians are necessary to operate it, thereby making treatment for lymphedema patients extremely expensive.
The following cited prior art references are relevant but distinguished from the present invention: U.S. Pat. Nos. 2,533,504, 2,699,165, 2,781,041, 2,943,859, 3,173,420, 3,454,010, 6,548,819, 3,561,435, 3,728,875, 3,845,769, 3,862,629, 3,885,554, 3,942,518, 3,975,929, 4,013,069, 4,030,488, 4,180,065, 4,320,746, 4,370,975, 4,374,518, 4,402,312, 4,552,133, 4,583,522, 4,773,397, 4,922,893, 4,938,208, 4,961,418, 5,108,426, 5,109,832, 5,117,812, 5,171,211, 5,172,689, 5,228,142, 5,233,974, 5,257,956 and 5,310,400.